1、Lessons Learned Entry: 1317Lesson Info:a71 Lesson Number: 1317a71 Lesson Date: 2002-12-02a71 Submitting Organization: JPLa71 Submitted by: David J. OberhettingerSubject: ESD: An Enduring and Insidious Threat to Flight Hardware (A Cornerstone Lesson) Abstract: A number of incidents, some of them docu
2、mented in other lessons learned, are listed to support the thesis that ESD remains an insidious threat to the integrity of flight hardware despite extensive NASA and industry experience with controlling ESD and its effects.The lesson references a number of NASA Reliability Preferred Practices that s
3、hould be implemented on flight projects. Description of Driving Event: Electrostatic discharge (ESD) remains an insidious threat to the integrity of flight hardware despite extensive NASA and industry experience with controlling ESD and its effects. ESD-induced damage during the latter stages of spa
4、cecraft development (e.g., system integration and test or launch vehicle integration) may be difficult to detect/analyze and expensive to repair. While the following NASA lessons learned do not define the total magnitude of the industry wide problem, they illustrate a sample of ESD-related issues:a7
5、1 On two occasions during integration and test of Mars Exploration Rover (MER), a braided ground strap being dragged across the floor contacted a facility power outlet, causing visible sparks and partial melting of the ground straps and power connectors. LLIS # 1372a71 Nitrogen tetroxide flowing thr
6、ough a flex line during Galileo spacecraft propellant loading caused an electrostatic discharge that perforated the flex line. The resultant leak of this highly toxic and corrosive substance posed significant risk to launch personnel and flight hardware. LLIS # 0217a71 The fire and destruction of a
7、Pershing II stage I missile motor was attributed to unreliable tests that indicated that the solid propellant was not sensitive to ESD. LLIS #0328Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Discrepancies reported with shipment of Robotic Work
8、 Stations pointed out the need for formal handling, packaging, and shipping processes to preclude improper ESD packaging. LLIS #1211a71 Electrostatic discharge from an ungrounded radiation “spot“ shield may have caused an anomaly during the Voyager I Jupiter encounter. This prompted a recommendation
9、 that metal spot shields and other metal masses on circuit boards should be grounded even if they are inside equipment housings. LLIS #0384a71 After an integrated circuit was damaged during installation of a discrete capacitor, it was determined that capacitors can accumulate a residual charge throu
10、gh normal handling and storage that is sufficient to destroy an integrated circuit. LLIS #0297a71 The continually decreasing feature size within integrated circuits makes modern electronic devices increasingly susceptible to ESD induced damage during handling and use. In addition, the effectiveness
11、of ESD protection circuits tends to decrease with decreasing device dimensions. LLIS # 1315a71 During receiving activities, a spark was observed upon the attachment of a facility ground strap to the Mars Exploration Rover (MER) Rover Electronics Module (REM). This re-emphasized that ESD is an issue
12、cutting across JPL hardware activities (Reference 1). LLIS # 1371a71 Some modern materials (e.g. certain composites) thought to be conductive have instead been found to be susceptible to surface charging. Use of such materials can allow ESD energy to be transmitted internally from exterior spacecraf
13、t surfaces and damage flight electronics. LLIS # 1330References: (1) Jet Propulsion Laboratory Corrective Action Notice No. Z77277, August 27, 2002.Additional Key Words: ESD Control Plan, ESD requirements, ESD sensitive devices, ESD sensitivity, personnel safety, system safetyLesson(s) Learned: Desi
14、gners of ESD-sensitive devices and handlers of ESD-sensitive equipment cannot assume that routine ESD engineering principles and practices will continue to be adequate to prevent damage to flight equipment.Recommendation(s): Plan implementation of the ESD-related practices documented in NASA Technic
15、al Memorandum 4322A, NASA Reliability Preferred Practices for Design and Test, including:a71 “Assessment and Control of Electrical Charges,“ LLIS #0654.a71 “Design Checklists for Microcircuits,“ Guideline LLIS #0680.a71 “Electrostatic Discharge Control in GSE,“ LLIS #0685.Provided by IHSNot for Resa
16、leNo reproduction or networking permitted without license from IHS-,-,-a71 “Spacecraft Thermal Control Coatings Design and Application,“ Practice No. PD-ED-1239.a71 “Electrostatic Discharge (ESD) Control In Flight Hardware,“ LLIS #0732.a71 “Design Practice to Control Interference from Electrostatic
17、Discharge (ESD),“ LLIS #0773.a71 “Electrostatic Discharge (ESD) Test Practices,“ LLIS #0777.a71 “Surface Charging / Electrostatic Discharge Analysis,“ LLIS #0788.a71 “Analysis of Radiated EMI From ESD Events Caused by Space Charging,“ LLIS #0797.a71 “Thick Dielectric Charging / Internal Electrostati
18、c Discharge (IESD),“ LLIS #0800.Evidence of Recurrence Control Effectiveness: Corrective Action Notice No. Z77277 was closed by JPL on September 5, 2003. The measures taken to implement Laboratory-wide corrective action on the above recommendations were (1) creating a procedure JPL QAP 61.12, “Packi
19、ng and Unpacking ESD Sensitive Hardware” (JPL DocID 61692) which is referenced by D-1348, “Electrostatic Discharge Control”, (JPL DocID 34906), (2) releasing a JPL-wide safety alert regarding the use of non-static-dissipative shipping containers, (3) Attaching ESD warning labels to all shipping cont
20、ainers, (4) releasing the JPL Electrostatic Discharge Control Document (JPL D-1348) Rev. F, and the Packing and Unpacking ESD Sensitive Hardware (JPL QAP 61.12), Rev. 0, (5) populating the JPL JIT Critical Environments catalog with “approved” ESD/Contamination control items, and adding warning state
21、ments to the catalog, and (6) adding a depiction of problem shipping containers to ESD Certification training courseware to augment current discussion of packing and unpacking procedures. Also, JPL is working on a course focused on the packing and unpacking of hardware that will be introduced to the
22、 QA engineers as part of their ESD Auditors certification, and JPL ESD Control Engineering is working with JPL Procurement to implement a controlled process for replacing all containers that are not static-dissipative.Documents Related to Lesson: N/AMission Directorate(s): a71 Exploration Systemsa71
23、 Sciencea71 Space Operationsa71 Aeronautics ResearchAdditional Key Phrase(s): a71 Energya71 Facilitiesa71 Flight EquipmentProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-a71 Flight Operationsa71 Ground Equipmenta71 Ground Operationsa71 Hardwarea71 In
24、dustrial Operationsa71 Launch Processa71 Occupational Healtha71 Packaging Handling Storagea71 Parts Materials & Processesa71 Payloadsa71 Personal Protective Equipmenta71 Safety & Mission Assurancea71 Spacecrafta71 Test FacilityAdditional Info: Approval Info: a71 Approval Date: 2003-01-14a71 Approval Name: Carol Dumaina71 Approval Organization: JPLa71 Approval Phone Number: 818-354-8242Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
